dmd daisi chaining

1.Are there formulas/equation related number od daisi chaining and microcontroller.
2.Must I isolated between mcu power supply and daisi-chaining power.suplly ?

Are there info's at url,who's success daisy chaining above.8'pieces or more like 16 pieces ?

Any info are welcome.

Huys Cobb

Re: dmd daisi chaining

Posted: Mon Feb 27, 2017 12:04 am

by Brissieboy

cobble,
There is a lot of information on these subjects on this forum. Try starting here for some DMD basics, but have a good look around.
There is a practical limit on how many DMDs you can drive with a single Uno - and it is a lot less than 8!! Also depends on what else you want you CPU to do. Better to have a master CPU which talks to several slaves each driving about 4 DMDs. Stryker (a user on this forum) has used this principle and there is more information on this forum.
There is no need to have separate power supplies, but your supply must be capable of supplying enough current for the full DMD load (which is quite high depending on the maximum number of LEDs lit). If you do use separate power supplies, you must common the negative rails.

Re: dmd daisi chaining

Posted: Tue Feb 28, 2017 11:04 am

by cobbler

Howdy
Thank you for info's

According to freetronix that max dmd was 6 with arduino.

I'm planning experiments with Atmega to reach daisi chaning 8 pieces.If that out of formula/equation then with Arm MCU.
At least could get 8-16 pieces for daisi chaining.

Briesseboy,Are the url from others ?

Regards

Huys Cobb

Re: dmd daisi chaining

Posted: Tue Feb 28, 2017 3:40 pm

by Loki

with arduino MEGA i have tested 7 - 10 without any problem on DMD (DMD2 is liitle slower in scrolling)

Re: dmd daisi chaining

Posted: Thu Mar 02, 2017 9:32 am

by cobbler

Howdy

Are there url who.s success with daisi-chaining ?
Brissieboy,did you possesed url for daisi-chaining ?

Regards
Huys Cobb

Re: dmd daisi chaining

Posted: Thu Mar 02, 2017 10:14 am

by stryker

They daisy-chain by design. Every project where there is more than one DMD module in use has them connected one after the other. The Arduino connects to the last DMD in the chain. Make sure you power them with something beefy, and if you use a different power supply for your Arduino to the DMD make sure you also connect the GNDs from each power supply together.

I found some photos of my demo board when I was assembling it. As Brissieboy noted above, it uses 3 slave modules which are coordinated. Each slave has no more than 4 DMDs attached in this board, but I've used 6 with an ATmega328P-AU based board (like a Uno).

The one of the back of the board may not be too helpful with all the duct tape holding things in place, but you can see the basic idea is the ribbon cables go from controller (in your case Uno) to the last DMD, to the previous...all the way to the first. In panels where they are arranged in rows that requires the ribbon to cross from the start of one row to the end of the previous.